1. Field of the Invention
The present invention relates to telecommunications networks, and more particularly to a system and method for accessing, monitoring and testing a telecommunications network.
2. Description of the Related Technology
For some time, public switched telephone networks (PSTN) have utilized time division multiplexing (TDM) transmission systems to communicate both voice and data signals over a digital communications link. For example, digital signal level 1 (DS1), and more recently digital signal level 3 (DS3), data paths have long been used to carry both voice and data signals over a single transmission facility. DS1 data paths carry DS1 signals which are transmitted at a transmission rate of 1.544 Mbps, and DS3 data paths carry DS3 signals which are transmitted at a transmission rate of 44.736 Mbps. Consequently, both DS1 and DS3 data paths offer the advantage of considerably reducing the number of lines required to carry information that otherwise would be required without time division multiplexing the digital voice and data signals.
Nowadays, there are telecommunications companies which provide local telecommunications service within numerous local access transport areas (LATA). These companies are forced to rely on interexchange carriers such as ATandT, MCI and Sprint for transmission of calls from one LATA to another. As a result, a long distance call or transmission from one end-user to another involves many levels of multiplexing and many transport carrier handoffs. The responsibility for quality and performance of the telecommunications circuit is thus split between local telecommunications companies and interexchange carriers.
Telecommunications companies often need an economical way to access circuits for testing and protocol analysis. Typically, each telecommunications company dispatches multiple repair crews with portable test equipment to a number of locations. The locations include the network boundary between the long distance and the local telecommunications company, the telecommunications building nearest the end-user, and to outside facilities such as the cables and equipment beneath streets and on poles between the central offices and the end-user customer. This method of maintenance results in significant inefficiencies. Hence, solutions which do not require dispatching repair crews with portable test equipment when problems occur were created. Today, telecommunications companies equipped with advanced systems can monitor circuits remotely from a network management center. However, with the split in responsibility among telecommunications companies comes significant difficulties in maintaining network circuits, troubleshooting and isolating transmission faults over their data paths: logical faults (which are protocol dependent) and physical faults (which are circuit dependent). Moreover, and perhaps more importantly, with data services and voice services sharing common networks, an organization maintaining a network common with another organization could easily access, interfere or disrupt circuit communications for the other organization.
Most network elements incorporate some form of monitoring, test, and control of the data that they process. However, none of these options supports the monitor-only function or restricted access (firewall) feature of the present invention. The U.S. Pat. No. 5,375,126 to Hekimian Laboratories, Inc., apparently describes a system which provides physical and protocol testing of digital data system (DDS). The Hekimian system, however, does not offer the firewall functionality of restricting or preventing a technician from accessing or interrupting unauthorized network circuits or other organization""s equipment.
Thus, a restricted access method that provides continuous performance monitor-only of DS3 embedded channels and technician access restricted to authorized equipment are desired. It is desired to have a system which provides comprehensive, full-time performance monitoring-only of DS3 embedded channels (i.e. DS1, DS0 and subrate channels) through a digital cross-connect system (DCS) or directly connected circuits. It is further desired to provide a system having restricted circuit access (firewall feature) by data network technicians to ensure that a network organization accesses only its own equipment or authorized facilities. With the restricted access feature, other organizations will no longer have to be concerned about unauthorized access to their circuits nor about interference or interruption caused by unauthorized access by data network technicians. In addition, it is also desired to provide testing of DS1, DS0 and subrate circuits, along with an extensive suite of test capabilities for HiCap, DDS and VF services only for authorized or core network technicians.
The present invention provides a protocol analysis access system (PAAS) and a restricted access method to allow telecommunications companies to monitor and test their communication networks without accessing or interfering with other restricted-access networks. From a telecommunications company""s network maintenance center, a data network technician can remotely monitor and test a network via an X.25, Ethernet, frame relay circuit, asynchronous RS-232 interface, or an ATM remote control link. By executing specific and a limited number of transaction language 1 (TL1) commands at the network maintenance center, the technician can perform non-intrusive and real-time access, monitor-only and testing of DS0 and DS1 signals. In addition, by allowing a technician to execute specific commands only, the technician is prevented from testing unauthorized equipment network, i.e. those networks with access restricted to xe2x80x9ccorexe2x80x9d network technicians.
In one aspect of the present invention, in a telecommunications network, a signal access system is provided comprising an analyzer capable of performing testing on a service layer, an interface device connected to the analyzer, wherein the interface device is capable of receiving a signal and performing non-intrusive monitor-only function on the signal, and an external command source providing commands to the interface device, wherein the commands include a monitor-only request.
Furthermore, in another aspect of the present invention, a signal access system is provided which is capable of restricting access to a signal of a selected circuit comprising an analyzer capable of performing testing on a service layer, an interface device connected to the analyzer, and an external command source providing commands to the interface device, wherein the commands include a test access request.
There are multiple configurations for the system of the present invention. In a first configuration as presently embodied, a technician transmits TL1 commands to a Test System Controller/Remote Test Unit (TSC/RTU) installed at a remote location to allow monitor and test access to a network through a digital cross-connect system (DCS). In a second configuration, a technician transmits TL1 commands to an Integrated Test Access Unit (ITAU) installed at a remote location to allow monitor and test access to a network directly. In both configurations, the technician has monitor and test access to a wideband signal using a Facility Access Digroup (FAD) port, and a narrowband signal using a Test Access Digroup (TAD) port. Furthermore, in order to perform service layer testing for a network circuit, a T1 based protocol analyzer is connected to the TSC/RTU (in case of DCS connection) or to the ITAU (in case of direct connection) through a FAD port for narrowband/wideband signal test access or a TAD port for narrowband signal test access. The ITAU or TSC/RTU performs non-intrusive testing (through monitor-only) on the signal and, when the testing is complete, the signal is passed on or released to the protocol analyzer. Subsequently, at the network maintenance center, a technician executes special commands using an external command source (ECS) and remotely controls the protocol analyzer via a separate control link to perform service layer conformance testing of the signal protocol implementation. When the test access is completed, the technician clears the test and instructs the ITAU or the TSC/RTU to release the port.